[tor-relays] 0.2.5.10 / 0.2.6.x and ticket 9682

[Tom van der Woerdt]

Sebastian Urbach schreef op 06/03/15 om 21:52:
> Dear list members,
>
> I hope that some of you compared 0.2.5.10 with 0.2.6.x regarding the
> performance (ticket 9682). How big/small is the difference in the wild ?
> I would appreciate it if someone with Linux / BSD could say a few words ;-)
>

Hi Sebastian,

As far as I can tell the change happened between 0.2.6.2 and 0.2.6.3 so 
I'll describe the performance difference between those.

Just had a look on a server of mine that is bottlenecked by the CPU. I 
noticed that there was indeed a big drop in CPU usage. However, there 
was also a similar drop in network usage, most likely caused by the 
restart. It took about a week to fully recover to normal levels.

It is incredibly hard to tell from the data whether there was a big 
performance difference as a direct result of the 0.2.6.2->0.2.6.3 
upgrade. It's definitely not going to be a 10% improvement, as far as I 
can tell.

Despite my nodes all running with 'NumCPUs 2', none of the worker queues 
seem to be doing much :

$ ps H -o etime,time,args -u toranon | grep node2
   3-01:46:17 1-20:35:33 /usr/bin/tor -f /etc/tor/torrc-node2
   3-01:46:13   00:17:09 /usr/bin/tor -f /etc/tor/torrc-node2
   3-01:46:13   00:17:09 /usr/bin/tor -f /etc/tor/torrc-node2

If those threads are what the patch addressed, I'm afraid it's not going 
to have a massive impact.

In case it's relevant: these measurements are taken from an exit relay 
with two processes each doing ~150Mbit/s (x2 if you count up+down).

Upgrade was done at 2015-02-24 21:26, relevant graphs :
  * cpu: 
http://www.imgdumper.nl/uploads8/54fa2a823bc62/54fa2a823434f-cpu.png
  * network: 
http://www.imgdumper.nl/uploads8/54fa2a8ce3db5/54fa2a8cdd05c-if_eth1.png

Tom

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